Astronomers are looking for continuous gravitational waves from Scorpius X-1
(ORDO NEWS) — John Whelan’s team at the Rochester Institute of Technology used data from the third round of LIGO-Virgo observations to search for continuous gravitational waves from Scorpius X-1.
Scorpius X-1 is a binary system consisting of a neutron star and its low-mass companion star V818 Scorpii. The system is 9,000 light years away.
The team has not yet detected a continuous stream of gravitational waves from Scorpius X-1, but that doesn’t mean there aren’t any. Scorpius X-1 is the strongest X-ray source in our sky (after the Sun).
Astronomers discovered it in 1962. Over the years, they have figured out that its strong X-ray emission comes from a neutron star with a mass equal to 1.4 solar masses.
A neutron star absorbs matter from its smaller companion, which has an estimated mass of 0.4 solar masses.
The strong gravitational field of a neutron star accelerates stellar material as it falls on the star. This overheats matter and causes it to emit X-rays.
The system is classified as a low mass X-ray binary system. The orbital period of these two objects is 18.9 hours.
Most of us are familiar with gravitational waves generated by black hole and/or neutron star mergers. The first detection of these waves occurred in 2015.
Since then, LIGO and its children KAGRA and Virgo have regularly detected these “stronger” waves. It is important to remember that these detections capture specific collisions – in fact, “one-time” events.
However, they are not the only sources of gravitational waves in the universe.
Astronomers believe that massive objects that rotate hundreds of times per second, such as neutron stars, could create weaker continuous waves that need to be detected.
So, what can cause waves in a binary neutron star-companion star pair? Look at the outer structure of neutron stars. Scientists describe them as uniformly smooth objects with strong gravitational and magnetic fields.
However, they may have tiny bumps on the surface (called “mountains”). They protrude only a fraction of a millimeter above the surface of the “crust” of a neutron star.
Mountains are actually deformations in this crust. They are created by extreme stresses in the electromagnetic field of a neutron star.
It is also possible that these deformations occur as the rotation of the object slows down. Or perhaps when its rotation suddenly speeds up.
However they form, they affect the neutron star’s magnetic and gravitational fields. Perhaps this is what causes gravitational waves.
The challenge is to detect and measure these waves. One day, astronomers will be able to capture the constant stream of waves emanating from Scorpius X-1.
The resulting data will tell more about the neutron star itself. This should also provide a clue to understanding the dynamics of this system.
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